About This Workout

Why fry in scorching summer temps when the fastest way to rock a cute suit is to tone below the water's surface? "The key is that water offers heavy resistance," says Igor Porciuncula, the cofounder of Boot Camp H20 in Los Angeles — 12 times the resistance of air to be exact. That means your moves engage more muscle fibers and burn more calories in a shorter amount of time. Snag a kickboard from poolside — we used a Bettertimes Hydro model ($10, swimtowin.com) — and do Porciuncula's shape-and-shred circuit twice through for sexy arms, tight abs, trim thighs, and zero dripping sweat.

Aqua Teaser

Targets shoulders, arms, abs, and hips

Standing in shallow end, simultaneously sit back into water, treading with hands out to sides, and lift both legs together so that you fold at hips to create a wide V shape, with head and toes just above surface.

Quickly bring knees to chest — or bring legs as straight as you can toward chest to make V less wide — then extend legs to return to V position.

Do 15 to 20 reps. Continue treading with hands for 1 minute.

MAKE IT EASIER: Skip knee tuck and simply hold V position for 1 minute.

Side Burpee

Targets abs, obliques, hips, and legs

Stand with feet hip-width apart, holding a dumbbell in each hand.

In deep end, hold on to edge of pool with right hand so that body is perpendicular to edge; tuck knees into chest to place both feet flat (right stacked above left) against side wall of pool as high as possible.

Maintaining hand grip throughout, jump feet off wall and extend legs as you engage abs to bring body as parallel to surface as possible in a side-plank position (left hip now stacked above right). Return to tuck and continue for 1 minute.

Water Taxi

Sit on kickboard with knees together, legs dangling or skimming bottom of pool.

Extend arms in front of you, palms facing away from each other, then sweep arms out to sides (as if doing a breaststroke).

Continue stroking across pool for 30 seconds, then switch stroke to go in opposite direction: Bring arms out to sides with palms facing forward, elbows slightly bent, then sweep arms together in front of you. Continue for 30 seconds, squeezing shoulder blades as you push forward and back.

Dolphin Tail

Targets abs and legs

Tread water in deep end of pool, arms out to sides and legs extended beneath you.

Engaging abs, squeeze legs together and sweep them backward, bending knees slightly, then quickly extend them forward (like a dolphin's tail); counterbalance motion by sweeping arms through water in opposite direction of legs.

Continue for 1 minute.

TRAINER TIP: Your whole body should crack like a whip; initiate the movement from your core, not your legs.

The Washboard

Targets back, shoulders, arms, and abs

In rib-deep or waist-deep water, stand with feet wide, grasping each end of kickboard with thumbs on top; hinge forward from hips 45 degrees with back flat and elbows bent by sides so that board is in front of chest.

Push kickboard diagonally down under water, extending arms and squeezing abs, then bend elbows to scoop board back up to chest like a biceps curl.

Continue for 1 minute.

TRAINER TIP: Splash as little as possible to ensure you're focusing on your core and arms.

Deck Dip

Targets triceps, abs, and obliques

Begin with your back facing side wall of pool and place palms on edge behind you, fingertips facing forward; bend left knee to place left foot flat against wall and raise straight right leg to hip height in front of you.

Straighten arms to lift out of water; lower to start.

Do 10 reps; switch legs and repeat.

MAKE IT EASIER: Keep both knees bent and both feet flat on wall. (If booty scrapes the edge, you can also do this in corner of pool.)